AMELIORATIVE EFFECTS OF SALICYLIC ACID ON SOME PHYSIOLOGICAL AND BIOCHEMICAL ATTRIBUTES IN MASHBEAN (Vigna mungo L. Hepper) UNDER NaCl STRESS

The study was conducted in an open air facility equipped with a rainout shelter to determine the effects of salicylic acid on growth, biochemical attributes and yield in mashbean genotypes varying in salt sensitivity. Plants were grown under saline and non-saline conditions in 27 cm diameter plastic pots. The saline treatment @ 3.0 and 4.5 ds m-1 NaCl was applied in split dose: at the time of sowing and 15 days after sowing. Salicylic acid @ 0.5 and 1.0 mM concentrations was sprayed at 25 DAS and observations were recorded at pod formation (65 DAS) stage. Increasing salt concentration adversely affected the plant height and leaf area at all the stages of development. A decline in leaf relative water content and water potential of leaves was observed under the influence of salt at both the concentrations in all the four genotypes. Salinity also decreased membrane permeability. A reduction in chlorophyll content, carotenoid content and Hill reaction activity in leaves was recorded under salt stress. Salt stress increased the levels of proline and different metabolites viz. total soluble sugars, total soluble proteins and free amino acids in the leaves. However, the tolerant genotypes registered greater increase as compared to sensitive ones. SA application conferred protection to the plants by improving plant height, leaf area, leaf relative water content and water potential in all the genotypes. The membrane permeability was restored and photosynthetic efficiency of plants was also enhanced. The level of various biochemical constituents in salt stressed plants was enhanced and it helped the plants to overcome the adverse affects of salinity. Significant reduction in seed yield and its attributes were recorded under both levels of salinity. SA application protected plants against salinity induced decline in yield components. The recovery was more pronounced at 3.0 ds m-1 salinity as compared to 4.5 ds m-1 salinity level particularly with 0.5mM SA.